Growth Responses and Mineral Nutrient Relations of Salt‐Stressed Sorghum

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Abstract
The production of sorghum [Sorghum bicolor (L.) Moench], a moderately salt‐tolerant crop, often occurs in areas of relatively low rainfall and on marginal soils containing excess salts. Despite the importance of sorghum to agriculture, relatively less is known about its response to these stressful environments than that of other major cereal grain crops. The purpose of this investigation was to study the effects of moderate levels of salinity on growth, assimilate partitioning, and mineral nutrient relations of a single cultivar of sorghum under both field and greenhouse conditions. Sorghum dry matter production decreased substantially in response to a moderate increase in soil electrical conductivity (2.1 to 5.9 dS m−1). Overall, total shoot and root dry weights of greenhouse‐grown plants decreased to a greater extent by moderate (−0.2 and −0.4 MPa) additions of isosmotic concentrations of NaCl than Na2SO4. However, at higher salinity levels (− 0.6 MPa), growth was more inhibited by Na2SO4. Sheath tissues of the leaves of NaCl‐stressed plants tended to accumulate chloride. Sodium concentrations in the roots of control and NaCl‐treated plants were significantly higher than in shoot tissues at all salinity levels. At higher concentrations of Na2SO4, this exclusion of Na from the shoot broke down and resulted in a dramatic increase in the Na levels of shoot tissue and concurrent decrease in K and Mg concentrations. Seminal roots contained more Ca, Mg, Cl, and Na, while adventitious roots were higher in K.